Scroll-type compressors are known in the prior art for use in refrigerators, air conditioners, etc. In some prior known compressors of this type, in order to prevent lubricating oil mixed in the refrigerant from being fed into the refrigeration cycle system, the oil is separated from the refrigerant while the compressed refrigerant is temporarily in the compressor's discharge chamber, and the separated oil is supplied to sliding parts, etc., in the compression mechanism unit by utilizing the pressure differential that is created between the discharge pressure (high pressure) and the intake pressure (low pressure) or their intermediate pressure which does not require power, thus eliminating the need for an oil pump or the like that requires power to operate.
In one such compressor, it is known as disclosed, for example, in Japanese Unexamined Patent Publication No. 2004-177020, to provide an oil separator outside the compressor and circulate the oil separated from the refrigerant back to the compressor after using the heat of the oil on the heat pump cycle side.
On the other hand, Japanese Unexamined Patent Publication No. 2006-266170 discloses a scroll compressor comprising a compression mechanism unit accommodated in a housing constructed as a sealed container, an oil separator for separating oil mixed in a refrigerant, and a high-pressure oil storage chamber for storing the separated oil, wherein the oil is fed from the high-pressure oil storage chamber back to the compression mechanism unit accommodated in the housing.
Further, Japanese Unexamined Patent Publication No. 2001-207980 discloses a compressor in which a compressor unit and a driving means are enclosed in a housing with a concave-shaped partition separating one from the other.
Of these compressor component elements, an invention concerning the oil separator is disclosed, for example, in Japanese Unexamined Patent Publication No. 2004-211550, in which the oil separator is contained within the housing of the compressor.
According to such structure, not only can the oil be prevented from flowing into the cycle and the cycle efficiency increased, but the reliability of the compressor can also be increased because the oil can be stored within the compressor.
On the other hand, Japanese Unexamined Patent Publication No. H10-37883 discloses an invention in which the oil separator is constructed separately from the compressor proper.
Further, of the compressor component elements, there is disclosed, as in the above-cited Japanese Unexamined Patent Publication No. 2004-211550, an invention concerning the high-pressure oil storage chamber in which the high-pressure oil storage chamber is contained within the housing of the compressor.
In the compressor disclosed in above-cited Japanese Unexamined Patent Publication No. 2004-211550, the high-pressure oil storage chamber is located adjacent to the discharge chamber in the compression mechanism unit within the housing where the oil separator is also contained. However, this has a problem that the compression mechanism unit, and hence the refrigerant drawn therein, is heated by the heat of the high-temperature, high-pressure oil, causing degradation of compressor efficiency. Furthermore, since the high-pressure oil storage chamber has to be placed below the oil separator, this compressor has a disadvantage that the oil storage capacity is small and a sufficient amount of oil cannot be stored.
In view of this, the applicant has previously proposed a scroll compressor in which a partition wall is provided so as to form a space between the compression mechanism unit and the high-pressure oil storage chamber within the container, thereby enhancing the performance by the resulting heat insulating effect while at the same time securing a sufficient oil storage capacity.
As described above, the compressor has problems yet to be overcome or alleviated as follows:
(1) Since the high-temperature oil in storage is in contact with the compressor proper, the gas drawn therein is heated, causing degradation of compressor performance.
(2) When the oil separator is contained within the housing, the area subjected to high temperatures within the housing increases, and the efficiency drops because the introduced refrigerant is heated; furthermore, since the oil storage unit has to be placed below the separation cylinder of the oil separator, the oil storage capacity decreases.
(3) When the oil separator is constructed separately from the compressor proper, the overall size of the compressor system increases because the compressor, oil separator, and accumulator are constructed as separate units.
(4) When a partition wall is provided so as to form a space between the compression mechanism unit and the high-pressure oil storage chamber within the container, since the interior of the heat insulating space is at a low pressure, the partition wall is slightly deformed due to the pressure from the high-pressure oil storage chamber. This deformation of the partition wall can lead to a breakage of the connecting portion between the oil return passage and the partition wall, causing the lubricating oil to leak from the high-pressure oil storage chamber.
(5) When CO2 is used as the refrigerant, since the housing is used in a high-pressure environment, the compressor unit and the driving means, both in a relatively low-pressure environment, are strained due to the high-pressure space separated by the partition wall.
Furthermore, when the high-pressure oil storage chamber is constructed integrally with the relatively low-pressure housing, since a partition wall having sufficient strength has to be provided, the overall size increases, and in addition, the joining portion between the high-pressure oil storage chamber and the low-pressure housing is strained and the joining strength decreases.
An object of the present invention is to solve the above problems.